To learn tourism, first it will depend on where you come from. You can choose a specialization like travel agents, hotel managers, adventure guides, tour guides and flight attendants are some people that work in the tourism industry. Carry out an online search for schools that focus in your desired field. Get more tips at http://www.ehow.com/how_7719298_learn-tourism-home.html.
Difficult question to answer... depends on where you live... Tourism requires a vast knowledge of the sites that would interest a tourist... this in turn requires a study in the historical, cultural and aesthetic value of those sites among other things to the potential tourist. Not all tourists have the same taste...
Some go for the beaches, some for architecture, some for the archeological value, some for shopping, some to gamble, some for indigenous therapy while some even go for sex!
Therefore, you should select what you are going to specialize in - hopefully not sex tourism!
Registering yourself with your local tourist board is a good step to take as a start. If they have programmes conducted for tourist guides then you could follow them for getting info on the sites... else you could make yourself an apprentice to an experienced guide / lecturer.
It is an attractive job...needs a long apprenticeship...the more experienced you are the better you will be... and then you could set up office in collaboration with major tour operators and the local hotel chains and individual hotels. All the best.